1. Field of the Invention
The present invention relates to a disc recording system, and more particularly, to a device and a method for decoding a disc read signal.
2. Description of the Prior Art
Within an optical disc such as a DVD, it is common that encoded data is arranged to perform error correction in 32 KB units of data. This error correction unit is referred to as an ECC block. FIG. 1 is an explanatory view showing a format of an ECC block contained in an optical disc. A format of the ECC block is arranged to be a two-dimensionally arranged data consisting of 172 words×192 rows and contains parity bits to be added in two error-correcting systems. These two kinds of error-correcting systems add parity bits that are referred to as a PI parity or a PO parity into the ECC block. These PI and PO parities are used when the encoded data is error-corrected by a Reed Solomon Product Code (RSPC). The technique mentioned above is well known in the art.
During an ECC decoding process, a parameter ρ, which is referred to as an erasure, is considered to represent a number of known error locations within an ECC block. The parameter of erasure is very helpful to the subsequent error-correction decoding operation. However, if the parameter ρ is of a large value which comes from false alarm due to an improper implementation of an ECC decoding circuit and/or some other causes, it would hinder the decoding capacity of the ECC decoding circuit. Additionally, if the parameter ρ is too large, it would be difficult for the subsequent error-correction decoding circuit to derive the ECC decoding process.